Method of making resilient pins



- Dec. 8,1970 w. R. EVANS 9 3,545,080

METHOD OF MAKING RESILIENT PINS Filed May 16, 1967 '4 Sheets-$11961; i

Dec. 8, 1970 w. R. EVANS METHOD OF MAKING RESILIENT PINS 4 Sheets-Sheet 2 Filed May 16, 1967 Dec. 8, 1970 w. R. EVANS 3,545,080

METHOD OF MAKING RESILIENT PINS Filed May 16, 1967 4 Sheets-Sheet 5 Dec. 8,1970 I w. R. EVANS METHOD OF MAKING RESILIENT PINS Filed May 16, 1967 4 Sheets-Shasta United States Patent O 3,545,080 METHOD OF MAKING RESILIENT PINS William Robert Evans, Hershey, Pa., assignor to AMP Incorporated, Harrisburg, Pa. Continuation-impart of application Ser. No. 612,125, Jan. 27, 1967. This application May 16, 1967, Ser. No. 642,639

Int. Cl. H02g 15/00 US. Cl. 29-629 1 Claim ABSTRACT OF THE DISCLOSURE A length of bar stock is flattened and reformed to produce a section having spring characteristics whereby the bar is capable of resiliently mating with a nonresilient article. Alternatively, a length of flat stock is stamped or etched to produce resilient members, the flat stock being rolled or left flat depending on a particular use.

CROSS-REFERENCE TO RELATED APPLICATION This application is a continuation-in-part of my earlier filed copending US. application Ser. No. 612,125, filed Jan. 27, 1967, now abandoned.

BACKGROUND OF THE INVENTION Field of the invention Male contact posts for mechanically or electrically mating with a female receptacle.

Description of the prior art Prior art posts are generally rectangular or circular in cross-section and are solid, non-resilient members. The posts mate with resilient sockets or eyelets.

SUMMARY OF THE INVENTION The invention provides a method of producing a pin having resilient properties. The basic advantage of such a pin is that it can mate with a stiff socket or eyelet. For example a pin could make electrical connection with a printed circuit board by simply drilling a hole in the board and plating the hole. The electrical contact would be provided by the resilience of the pin so no special socket or the like is required on the board. Also, the pin can be produced with no scrap and a natural lead-in is formed for ease in mating.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of the length of bar stock;

FIG. 2 is a perspective view showing the bar of FIG. 1 subsequent to a forming operation;

FIG. 3 is a perspective view showing the bar of FIG. 2 after a subsequent forming operation;

FIG. 3A is a cross-sectional view taken along the line 3A-3A of FIG. 3;

FIG. 4 is a perspective view showing an alternative method of production;

FIG. 4A is a cross-sectional view of a pin similar to that shown in FIG. 4;

FIG. 5 is a perspective view showing the pin of FIG. 4 after a subsequent forming operation;

FIG. 5A is a cross-sectional view taken along the line 5A5A of FIG. 5;

FIG. 6 is a view partly in section showing a typical application of a pin made according to the present invention;

FIG. 7 is a cross-sectional view showing the mating action between a socket and the pin of the instant invention;

FIG. 8 is a perspective view of a length of flat stock used in a further embodiment of the invention;

3,545,080 Patented Dec. 8, 1970 FIG. 9 is a perspective view of a pin formed from the stock of FIG. 8;

FIG. 10 is a cross-sectional view taken along the line 12-12 of FIG. 9;

FIG. 11 is a perspective view of a length of flat stock used in another embodiment of the invention;

FIG. 12 is a perspective view of a pin formed from the stock of FIG. 11;

FIG. 13 is a perspective view partly broken away showing details of the pin of FIG. 12;

FIG. 14 is a cross-sectional view taken along the line 1616 of FIG. 12;

FIG. 15 is an exploded perspective view showing a further form of pin being produced from flat stock;

FIG. 16 is a plan view of an etched circuit embodying the present invention; and

FIG. 17 is an exploded perspective view showing the present invention applied to an integrated circuit module.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The attainments of the present invention will become apparent to those skilled in the art upon a reading of the following detailed description when taken in conjunction with the drawings in where there are shown and described illustrative embodiments of the invention; it is to be understood, however, that these embodiments are not intended to be exhaustive nor limiting of the invention but are given for purpose of illustration in order that others skilled in the art may fully understand the invention and the principles thereof and the manner of applying it in practical use so that they may modify it in various forms, each as may be best suited to the conditions of a particular use.

A pin according to the present invention is produced from a length of bar stock such as shown in FIG. 1 and indicated at 10. The bar may be of rectangular, circular or other cross-sectional configuration. For ease of illustration a bar of circular cross-section has been shown, such bar being of generally uniform cross-sectional area throughout the major portion of its length.

The pin 10 is normally formed of a metallic material which is electrically conductive and of any suitable length and cross-sectional area. The first step in the production of the pin is to substantially flatten a section of the pin as indicated at 12. The flattened section 12 may then be formed into a generally U-shaped section as shown in FIGS. 3 and 3A whereby a section 14 is produced which is capable of resilient flexing action. The periphery of section 14 is greater than that of the remainder of pin 10 and therefore the pin can mate with an eyelet or socket just slightly larger than the non-resilient portion of the pm.

An alternative method of producing the pin is shown in FIG. 4 wherein the flattened portion 12 is provided with a blanked out slot 16. The pin shown in FIG. 4 may then be formed by turning the strips 18 and 20 at substantially right angles to the plane of the flattened portion 12 into a position as shown in FIGS. 5 and 5A. The strips 18 and 20 may be given a generally arcuate configuration during the forming operation. The spring section 22 thus produced in the pin has considerably more resiliency than the section 14 formed in the pin of FIG. 3 since the strips 18 and 20 are substantially free for resilient movement toward and away from each other. The forming operations performed on the pin may be accomplished by conventional forming tools and may be accomplished in either the hot or cold material state.

FIG. 4A illustrates a pin in its final form which is quite similar to the pin of FIG. 4. The flattened section 12' is not flattened to the extent of section 12 (FIG. 4) leaving strips 18 and 20' capable of flexing motion through the slot 16'. The degree to which the section 12' is flattened depends on the amount of resiliency required and on the desired external dimension of the section since an extremely flattened section would have low resiliency and a large external dimension and vice versa. The section can, of course, be adjusted to size by manipulating the strips 18' and 20'.

The pins of the present invention have general utility in mechanical and electrical applications. One application of the pins is shown in FIG. 6 wherein the pin 30 is mounted in a housing member 32 and cooperates with an aperture 34 formed in a printed circuit board or the like 36. The aperture 34 is plated at 38 with an electrically conductive material, which plating extends as shown at 38' to additional circuitry on the printed circuit board. The actual mating action can be seen in FIG. 7 wherein a pair of pine 30a and 30b are shown in relation to a pair of sockets 38a and 38b. Pin 30a is just entering socket 38a while pin 30b is seated within the socket 38b and the resilient section of the pin has been compressed by the socket. The resilient pin section will maintain the pin in position and will also provide for an excellent electrical connection between the pin and socket.

The various pins described above and shown in FIGS. 3, 4, and illustrate the present invention as applied to round wire or bar stock. However the present invention is not limited to stock having a circular cross-section but rather the principle of a resilient pin, that is a pin having a spring section, may be applied to fiat stock as well as round. The following description teaches various methods of producing a resilient pin from flat stock.

In FIG. 8 there is shown a strip of flat stock 40 from which a resilient pin is to be produced. The stock 40 has a central slot 42 and a pair of edge slots 44 formed therein, the edge slots 44 being approximately one-half of the central slot 42. The slots may be formed in the stock by a stamping operation, by chemical etching or by other convenient methods. The forward portion of the stock is charfered at 46 to provide lead-in for the pin as will be apparent as this description proceeds. The remaining portion of stock 40 is not shown in FIG. 8 but would be connected, in practice, to electrically conductive means according to the particular application made of the resilient pin. In FIG. 9 a pin 50 is shown which has been formed b the flat stock 40 after having been rolled into a cylindrical configuration. The pin is rolled about an axis generally parallel to the major extent of the slots 42 and 44 thereby producing the pair of resilient members 52 on opposite sides of the slot. Preferably the members 52 are bowed outwardly to present a diameter larger than that of the main portion of the pin. The bowing operation may be performed simultaneously with the rolling operation or may be a separate step achieved by a mandrel or the like. The chamfered edge 46 of the pin can thus be seen to provide appropriate lead-in for the pins entry into a mating receptacle.

In FIG. 11 there is shown a blank of flat stock 54 which is similar to the stock 40 shown in FIG. 8. Stock 54 has formed therein two central slots 56 and 58 and two edge slots 60. By providing two central slots the contact will produce three spring members 62 rather than two as formed in the pin of FIG. 9. In FIG. 12 a pin '64 is shown which represents the formed-up configuration of the flat stock 54. The pin 64 differs from the pin 50 previously described by the provision of the three spring members 62. The three spring members permit a greater force to be exerted in a radially outward direction than could be exerted by the two spring members and thus yields a pin which is capable of improved mechanical retention in a socket and improved electrical mating characteristics. The three spring members 62 are disposed at approximately 120 from each other as best seen in FIGS. 13 and 14 and provide equal distribution of forces between the pin and its mating receptacle.

In FIG. 15 there is shown a pin 66 which has been blanked or stamped from a piece of fiat stock 68. The pin is formed by stamping a generally oval piece 70 from the center of the stock and also stamping a pair of edge portions 72 which surround the oval portion 70 but are slightly spaced therefrom in order to produce the pair of resilient members 74. The pin 66 needs no subsequent forming operation since the surved spring members 74 will function in their flat condition. This version of the pin, in most instances, will exert lower radial forces as compared to the pins of FIGS. 9 and 12. Pin 66 is primarily useful for mechanical retention and may be soldered or otherwise connected to a mating receptacle in order to complete an electrical connection.

FIG. 16 shows a typical etched circuit for use in an integrated circuit or flat pack such as 76 shown in FIG. 17. The circuitry of FIG. 16 is shown as including the teachings of the present invention in that the outer ends of each circuitry strip is provided with a resilient pin as indicated at 78. The circuitry of FIG. 18 is secured to an integrated circuit in a manner well known in the art and the pin portions 78 are bent at 90 as seen in FIG. 19 to enable the fiat pack to be plugged into appropriate sockets 80 disposed in a printed circuit board or the like 82. The sockets 80 for receiving the pins 78 may be circular as shown in the figure or may be of rectangular configuration. These sockets in their simplest form may merely be plated through holes consisting of a metallic liner 84 which connects with external circuitry on the board 82. The pins 78 will be received in the socket and will be pressed inwardly to cause a firm mechanical union between the pin and socket. If desired, the pin may then be soldered to the socket.

Changes in construction will occur to those skilled in the art and various apparently different modifications and embodiments may be made without departing from the scope of the invention. The matter set forth in the foregoing description and accompanying drawings is offered by way of illustration only. The actual scope of the invention is intended to be defined in the following claim when viewed in its proper perspective against the prior art.

What is claimed is:

1. A method of producing a resilient pin from a bar of substantially uniform cross-section comprising the steps of forming an intermediate portion of said bar into a substantially flattened condition whereby material is forced beyond the lateral periphery of said bar, forming an elongated slot in said flattened portion only, said slot being formed on and parallel to the axis of said bar, subsequently turning the flattened material on both sides of the slot in opposite directions and into confronting walls in parallel relation and on opposite sides of the bar axis and bowing the opposite walls outwardly beyond the periphery of the bar thereby constituting resilient members integral between the bar ends capable of flexing motion toward and away from each other.

References Cited UNITED STATES PATENTS 1,103,481 4/1914 Buren 163-5 255,808 4/1882 Peberdy 163-5 1,376,735 5/1921 Kring 339-252 2,004,555 6/1935 Kleinmann et al 339-252 2,032,017 2/1936 Hocher et al 113-116 2,064,545 12/1936 Kleinmann et al. 339-252 3,087,136 4/1963 Peterson et al 113-119X 3,340,491 9/1967 Deakin 317-101 680,373 8/1901 Devine 24213 739,762 9/ 1903 Washburne 24-213 2,192,573 3/1940 Dunajeif 9-163 (Other references on following page) 5 STATES PATENTS UNITED 3/1942 Place 24213 8/1944 Krause 2427 11/1951 Leven 140111X 1/ 1961 Fernberg 24-213 3/1965 Mears 29--163 9/1968 Reid 29622X 9/1966 Solum 29163.5X

6 456,243 2/1928 Germany.

JOHN F. CAMPBELL, Primary Examiner R. W. CHURCH, Assistant Examiner US. Cl. X.R. 

